Home · Register · Search · View Winners · Software · Hosting · Software · Join Upload & Sell

Moderated by: Fred Miranda
Username   Password

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Canon Forum | Join Upload & Sell

  

Archive 2013 · Strange IS lens blur issue
  
 
Cphoto1954
Offline
• • •
Upload & Sell: On
p.1 #1 · p.1 #1 · Strange IS lens blur issue


I have owned Canon IS (image stabilization) lenses for close to a decade now and shot well over 100K images with them over that time. There are occasions, where I notice a strange phenomenon where most of the image will be sharp but an area of it, will be blurry.

Most of the time everything is hand-held and keeping everything as steady as possible. Many exposures are not even that slow at times.

Iíve attached some examples of and image shot at 1/80 sec at f11 with a 24-105 IS lens set to 70mm. Notice how one is blurry in a small section (near the colored post) and the other is just fine. Actually the tree just to the left of the blurry one is as sharp as the non-blurry one. These were shot about 20 seconds apart, with the blurry one shot first in sequence. I have included the full image too for reference so you can see the affected area in context. Both images, except for that one part, are equally sharp overall.

So what about you, have you seen this before? Your thoughts are welcomed, but my experience has taught me to always shoot at least two images if possible.






SHARP - IS







BLUR - IS







FULL IMAGE - SHARP IS




Jan 10, 2013 at 10:27 PM
jcolwell
Offline
• • • • • • •
Upload & Sell: On
p.1 #2 · p.1 #2 · Strange IS lens blur issue


Strange. I've seen local, small-scale variation in atmospheric conditions do weird things, but I can't say that it explains this. OTOH, maybe it does.


Jan 10, 2013 at 10:46 PM
BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #3 · p.1 #3 · Strange IS lens blur issue


To me it also looks like the lower "left-of-center" area has more blur than the upper section. If almost looks like a sticking shutter blade, but if it only happens with that lens, and only when IS is engaged, then I suppose it could be a "hiccup" in the IS system causing a slight lens shift during exposure.


Jan 10, 2013 at 10:46 PM
Gunzorro
Offline
• • • • •
Upload & Sell: On
p.1 #4 · p.1 #4 · Strange IS lens blur issue


It's probably some sort of mechanical flutter -- either the shutter, or more likely the IS element on the stage of the shutter cycle. Notice the snow all along the bottom is blurry, as is the base of the largest tree on the far left. The next small tree to the right is also blurring, and moreso at its base. I'd like to see the entire image in extreme detail, piece by piece to note all affected areas.

Do you often shoot in near freezing conditions? Ever noticed the blur on other occasions? If it is a mechanical problem, I'm thinking there is a lubrication or hardening of some flexible piece causing this.

I've had IS blur affect photos, but that is always the entire image, not a section. So the shutter is involved somehow.

It may simply be the IS element started to move (vibrate) quickly at the beginning or end of the shutter cycle.

From experience (and I think some reading), 1/30 to about 1/100 is the "danger zone" for handheld IS shooting. The problem is you can be capable of holding the camera still enough that you are like a tripod -- fixed dampening of the vibration -- making the IS over-react and induce blur instead of stability.

That's my Photo CSI for the day! (show me blood splatters next!)



Jan 10, 2013 at 10:59 PM
skibum5
Offline
• • • • • •
Upload & Sell: Off
p.1 #5 · p.1 #5 · Strange IS lens blur issue


I think IS can cause weird things at times if you trigger a shot while it is spooling up or if it is just starting to do a sudden hitch to catch up to your moving the lens around large scale while using it, where it's not uniform. Sometimes when I accidentally left it on for soccer I thought I saw some odd stuff at times as well as more focus missed outright.

Of course so can atmospherics too.



Jan 10, 2013 at 11:01 PM
Cphoto1954
Offline
• • •
Upload & Sell: On
p.1 #6 · p.1 #6 · Strange IS lens blur issue


Very good thoughts and observations everyone! Keep 'em coming, if you have any more.

I was in the car when I shot it but was outside for about 2 minutes before that snapping a few (those were all fine) and yes it was just below freezing, but not crazy cold.

Glad to email full rez files if anyone wants the two images, just let me know.



Jan 11, 2013 at 03:51 AM
 

Search in Used Dept. 



snapsy
Online
• • • •
Upload & Sell: On
p.1 #7 · p.1 #7 · Strange IS lens blur issue


Cphoto1954 wrote:
I was in the car when I shot it but was outside for about 2 minutes before that snapping a few (those were all fine) and yes it was just below freezing, but not crazy cold.

Gunzorro comments sound right. I wonder if the motion from the car might factor into it as well.



Jan 11, 2013 at 03:59 AM
Cphoto1954
Offline
• • •
Upload & Sell: On
p.1 #8 · p.1 #8 · Strange IS lens blur issue


The car engine was off and not moving.



Jan 11, 2013 at 05:49 AM
Gunzorro
Offline
• • • • •
Upload & Sell: On
p.1 #9 · p.1 #9 · Strange IS lens blur issue


There wouldn't be any atmospheric effects at that distance (and unlikely at that temperature), so I'd rule that out.

I doubt the camera became icy cold to the core -- not like hiking in sub freezing conditions for extended periods.

The more I think about it, I think it was a flutter of the IS kicking in or out at the beginning or end of the shutter actuation. Odd for sure, but I doubt there was any problem with the camera.

Do some more shooting in similar type situations (without freezing snow is fine -- try to match camera settings) an keep an eye on your images and see if there is any recurrence in normal use.



Jan 11, 2013 at 06:13 AM
aekurth
Offline

Upload & Sell: Off
p.1 #10 · p.1 #10 · Strange IS lens blur issue


It sounds like you may have taken the blurred images from an open car window. The warm air escaping from the car could have moved into your field of view. This could have blurred portions of the image.


Jan 11, 2013 at 06:35 AM
Dark Slider
Offline
• • •
Upload & Sell: Off
p.1 #11 · p.1 #11 · Strange IS lens blur issue


When taking a picture, all of the image is not exposed at the same time. Even though the shutter speed of this shot has the shutter fully open for some duration, the leading shutter sweeps across the sensor (exposing some parts before others begin exposing) and the trailing shutter sweeps across the sensor (continuing to expose some parts after other parts have completed exposure.)

If there is image movement during either of these times, parts of the image will see blur, and other parts will not. If the image stabilizer was not fully settled before the first shutter started moving but finished settling before the shutter fully opened, then the part that was covered during stabilizer settling would be sharp and the part that was uncovered will be blurry. If there is lens movement while the picture is being taken, and the image stabilization runs out of range (hitting the hard stop) while the trailing shutter is mid-sweep, again parts of the image will be sharp and other parts will be blurry.

It is all in the timing and the mechanics.



Jan 11, 2013 at 06:37 AM





FM Forums | Canon Forum | Join Upload & Sell

    
 

You are not logged in. Login or Register

Username   Password    Retrive password